Photochromic ultra-violet ray shield powder, method of manufacturing the same, and skin external preparation using the same

ABSTRACT

A photochromic ultra-violet ray shield material principally composed of titanium oxide particles, which have a specific surface area of 25 m2/g or above and also have ΔE=5≦A (discoloration degrees) and B (at restoration)&lt;ΔE=3, a method of manufacturing the same and a skin external preparation using the same. Both photochromic property and excellent ultra-violet ray shield effect are obtained.

This application is a file wrapper continuation of application Ser. No.08/372,910, filed Jan. 17, 1995, which is a continuation of applicationSer. No. 07/896,615 filed Jun. 10, 1992.

FIELD OF THE INVENTION

This invention relates to photochromic ultra-violet ray shield powdermethod of manufacturing the same and skin external preparation using thesame and, more particularly to imparting ultra-violet ray shield powder,principally composed of titanium oxide, with the photochromic property.

BACKGROUND ART

The property of changing color when one substance is irradiated withlight and then returning to its original color when the lightirradiation is stopped, is referred to as the photochromic property orphototropic property. This property is utilized for color controlglasses or the like containing photochromic materials.

In the field of cosmetics, color variable make-up preparation whichutilize the photochromic property and permit enjoyment of color changes,is well known (as disclosed in Japanese Patent Application Laid-Open49312/1981, Japanese Patent Application Laid-Open 10079/1981 and PCT WO89/12084), and their applications in broader fields are expected.

Meanwhile, in the field of cosmetics there is problems of adverseeffects of ultra-violet rays on the skin, and ultra-violet ray absorbersfor absorbing ultra-violet rays and also ultra-violet ray shield powderfor shielding ultra-violet rays have been developed.

A typical example of the ultra-violet ray shield powder is fine particletitanium oxide which can scatter ultra-violet rays, and also there istitanium oxide having photochromic property. Therefore, photochromictitanium oxide which has both of these properties has been thought of.

SUMMARY OF THE INVENTION

The present invention has been intended in the light of the aboveproblems in the prior art, and its object is to provide a Photochromicultra-violet ray shield powder, which has both ultra-violet ray shieldeffect and excellent photochromic property.

To attain the above object of the invention, the inventors haveconducted extensive researches and investigations conditions forimparting Nine particle titanium oxide with the photochromic propertyand agglomeration properties. They found that powder having excellentphotochromic property and ultra-violet ray shield effect could beobtained by manufacturing it under specific conditions in correspondenceto the specific surface area of the material fine particle titaniumoxide. The invention is completed on the basis of this finding,

According to claim 1 of the present application, there is provided aphotochromic ultra-violet ray shield powder principally composed ofparticles with specific surface area of 25 m² /g or above and A≧5 andB≦3, A and B being determined as follows

4 g of the powder is uniformly dispersed in 16 g of nitrocelluloselacker to form a dispersion, which is coated on art paper using anapplicator to form a coating film with thickness of 76 μm, which coatingfilm is in turn dried to be used as a sample for photochromic propertymeasurement under an optical condition that a lame ("FL20S.BLB"manufactured by Toshiba) and a lamp ("FL20S-E" manufactured by Toshiba)are secured at a distance of 11 cm from each other. Distance adjustmentof the sample is effected using an ultra-violet ray intensity measuringapparatus ("SUV-T" manufactured by Tolay Technso) such that theintensity of ultra-violet rays incident on the sample is 2 mW./cm².

(1) The sample is colorimetrically measured after it has been left atroom temperature and in a dark place for about 10 hours the measurementbeing made using a colorimeter ("CR-200" manufactured by Minolta).

(2) The sample is immediately colorimetrically measured when it isdarkened by irradiation with the ultra-violet rays for 30 minutes insame way as described above.

(3) The irradiated sample is similarly colorimetrically measured afterleaving it at room temperature and in a dark place for 24 hours.

A represent the color difference ΔE between the color determined in (1)and the color determined in (2).

B represents the color difference ΔE between the color determined in (1)and the color determined in (3).

According to claim 2, there is provided photochromic ultra-violet rayshield powder, which is principally composed of titanium oxide.

According to claim 3, there is provided photochromic ultra-violet rayshield powder, which contains at least 50% of anatase type titaniumoxide.

According to claim 4, there is provided photochromic ultra-violet rayshield powder, which contains a photochromic property imparting agentmetal Me such that

    0.05≧MeO.sub.m /(MeO.sub.m +TiO.sub.2)≧0.0001

m=1/2, 1, 3/2, 2 or 3.

According to claim 5, there is provided a photochromic ultra-violet rayshield powder obtainable by calcinating material titanium oxide with aspecific surface area of 100 m² /g or above at a temperature of 700° C.or below.

According to claim 6 there is provided a method of manufacturingphotochromic ultra-violet ray shield powder, which comprises the step ofcalcinating material titanium oxide with a specific surface area of S₀m² /g (S₀ being 100 or above) at a temperature of T° C. calculated byrelations (1) below;

Relations (1):

    T(S.sub.0 +10)/0.10

400≦T≦600

According to claim 7, there is provided a method of manufacturingphotochromic ultra-violet ray shield powder, in which the photochromicproperty imparting agent metal being in the form of salt or alkoxide andprecipitated by solution of the salt or the alkoxide by neutralizationor hydrolysis reaction.

According to claim 8, there is provided a method of manufacturingphotochromic ultra-violet ray shield powder, the pH is controlled to 8to 11 during the neutralization.

According to claim 9, there is provided a skin external preparationcontaining 0.1 to 60% by weight of the photochromic ultra-violet rayshield powder.

Now, the constitutions of the invention will be described in detail.

Titanium oxide used as material according to the invention may betitanium dioxide lower titanium oxide, etc. These titanium oxidevarieties may be used in combinations. Titanium dioxide may be ofanatase type, rutile type and amorphous. Any of these varieties may beused. Suitably, at least 50% of anatase type titanium oxide may becontained because in this case satisfactory photochromic property can beobtained. The particles may be indefinite, flaky or spherical in shape

The material titanium oxide used according to the invention may be thoseobtained by a gaseous phase process, a liquid phase process and variousother processes.

The gaseous phase process is one, in which halotitanium in the form ofvapor or gas is decomposed at a high temperature together with anoxidizing agent or a hydrolysis agent to obtain titanium oxide.

The liquid phase process is one, in which titanium tetra-iso-propoxideor the like subjected to hydrolysis to obtain titanium oxide,

The size of the titanium oxide particles after calcinating is suitably25 m² /g or above, preferably 40 to 100 m² /g, in terms of the specificsurface area. If the size is less than 25 m² /g or greater than 100 m²/g, the ultra-violet ray shield effect tends to be reduced.

The proportion of titanium oxide used in the manufacture of photochromicfine particle titanium oxide, is suitably 95.0 to 99.99% by weight.

Examples of the metal used to impart titanium oxide with thephotochromic property, are iron, zinc, aluminum, silicon, etc. Thesemetals may be used in the form of their powder or as their salts, e.g.sulfates, chlorides, nitrates and acetates, or oxides, hydrates,hydroxides, etc. The photochromic property may also be imparted usingcobalt, cerium, etc. In this case, however, the powder itself iscolored, undesirably making it difficult in actual practice to observethe photochromic property.

Particularly, metallic iron powder and iron compounds are suitable fromthe standpoints of the safety in human use and imparting with thephotochromic property. According to the invention, metallic iron powderand iron compounds may be used alone or in their suitable combinations.Examples of the iron compound are salts of iron, e.g. iron sulfate, ironchloride, iron nitrate, iron acetate, etc., and also iron oxide and ironhydroxide.

The proportion of the metal used to impart with the photochromicproperty in the manufacture of photochromic titanium oxide, is suitably0.1 to 5.0% by weight, preferably 0.5 to 1.5 by weight. If theproportion of the metal is insufficient, it is liable to result ininsufficient photochromic property. If the proportion is excessive, onthe other hand, undesired coloring is liable.

Further, according to the invention it is possible to compound thephotochromic ultra-violet ray shield powder with other inorganic ororganic compounds For example, the photochromic fine particle titaniumoxide may be mixed with or compounded by means of coating or calcinatingwith one or more members of the group consisting of inorganic compounds,e,g., mica, sericite, talc, kaolin, silica, barium sulfate, iron oxide,chromium oxide, copper oxide, nickel oxide, vanadium oxide, manganeseoxide, cobalt oxide, calcium oxide, magnesium oxide, molybdenum oxide,zinc oxide, iron, chromium, copper, nickel, vanadium, manganese, etc.,and organic compounds, e.g., nylon, polymethyl methacrylate,polystyrene, epoxy resins, polyethylene, etc.

Further, ordinary titanium oxide may be compounded with other inorganicor organic compounds to impart with the photochromic property.

A composite material containing photochromic titanium oxide may beobtained by adding 0.1 to 0.5% by weight of metallic iron particles oriron compounds to a composite material such as titanium-mica ortitanium-talc coated with titanium dioxide by a dry process using a ballmill or the like or by a wet process of adding the system in the form ofan aqueous solution and then calcinating the resultant system. In analternative method, a titanium dioxide composite material by means ofthe hydrolysis of titanyl sulfate in the presence of metallic ironpowder or iron compounds and then calcinated.

According to the invention, the composite material containingphotochromic titanium oxide may be used after subjecting it to surfacetreatment, e.g., silicone treatment, surfactant treatment, surfacealkoxyl treatment, metallic soap treatment, fatty avid treatment,fluorine resin treatment, wax treatment, etc. By improving tempdispersion property in this way, it is possible to further improve theultra-violet ray shield performance and photochromic property.

When using the photochromic ultra-violet ray shield powder for a shinexternal preparation, its proportion in the total composition issuitably 1.0 to 60.0% by weight, preferably 5.0 to 20.0% by weight. Ifthe proportion is less than 1% by weight, the color change function maynot be provided. If the proportion is over 30% by weight, on the otherhand, the color change degree may often be excessive.

When flaky titanium oxide is used to manufacture the photochromicultra-violet ray shield powder, the proportion in the total compositionis suitably 10 to 60% by weight, preferably 10 to 40% by weight. Thereason for increasing the proportion compared to the case of using thefine particle titanium oxide as the material, is that the color changedegree per unit weight is reduced with increased particle size of theflaky titanium oxide.

Likewise, when incorporating the fine particle photochromic ultra-violetray shield powder is incorporated in a foundation or a powdery make-uppreparation such as loose powder or pressed powder, it is suitablyincorporated in 1 to 30% by weight. If its content is less than 1% byweight, sufficient photochromic property cannot be obtained. If thecontent is over 30% by weight, on the other hand, excessive color torechange is liable.

When using flaky titanium oxide as titanium oxide, it is suitablyincorporated by 10 to 60% ban weight with respect to powdery cosmetics.

When the fine particle photochromic titanium oxide in liquid cosmeticssuch as sun oil, it is suitably incorporated in 1 to 30% by weight.

If the proportion exceeds 30% by weight, the viscosity will excessivelyincreased, and in this case it is difficult to provide the function ofthe liquid cosmetics.

The composition incorporating the photochromic ultra-violet ray shieldpowder according to the invention, may suitably incorporate, if desired,other components usually used for the compositions of cosmetics or thelike. For example, it may incorporate inorganic powder, e.g., talc,kaolin, mica, sericite, white mica, gold mica, synthetic mica, red mica,black mica, rithia mica, vermicurite, magnesium carbonate calciumcarbonate, diatomaceocus earth, magnesium silicate, calcium silicate,aluminum silicate, barium silicate, barium sulfate, strontium, silicate,tungstate metal salts, silica, magnesium oxide, calcium oxide, zeolite,boron nitride, ceramic powder, etc., organic powder, e.g., nylon powderpolyethylene powder, benzoguanamine powder, tetrafluoroethlyene powder,fine crystalline cellulose, etc., inorganic white pigments, e.g.,titanium dioxide, zinc oxide, etc., inorganic red pigments, e.g., ironoxide (red iron oxide), iron titanate, etc., inorganic brawl pigments.e.g., γ-iron oxide, etc., inorganic yellow pigments, e.g., yellow ironoxide, less, etc., inorganic black pigments, e.g., black iron oxide,carbon black, etc., inorganic violet pigments, e.g., mango violet cobaltviolet, etc., inorganic green pigments, e.g., chromium oxide, chromiumhydroxide, cobalt titanate, etc., inorganic blue pigments, e.g.,ultramarine, red marine, etc., pearl pigments, e.g., mica coated withtitanium dioxide, bismuth oxychloride coated with titanium dioxide,bismuth oxychloride, talc coated with titanium oxide, mica coated withcolored titanium oxide, etc., metal powder pigments, e.g., aluminumpowder, copper powder, etc., such organic pigments as "Red No, 201","Red No,. 202", "Red NO. 204", "Red No. 205", "Red No. 220", "Red No.226", "Red No. 228", "Red No. 405", "Orange No. 203", "Orange No. 204","Yellow No. 205", "Yellow No. 401", "Blue No. 404", etc. and suchorganic pigments as "Red No. 3", "Red No. 104", "Red No. 106", "Red No.227", "Red No. 230", "Red No. 401", "Red No. 505", "Orange No. 205","Yellow No. 5", "Yellow No. 202", "Yellow No. 203", "Green No. 3", "BlueNo. 1", zirconium, barium, aluminum lake, etc., natural dyestuffs, e.g.,chlorophyll, β-kalotin, etc., various hydrocarbons e.g., squalane,liquid paraffin, vaseline, microcrystalline wax, ozokelite, serecile,cetylalcohol, hexadecylalcohol, oleilalcohol, cetyl-2-ethyl hexanoate,2-ethylhexyl permiate, 2-octyldodecyl myristate, 2-octyldodecylgum esterneopentylglycol-2-ethyl hexanoate triglyceril iso-octanoate2-ocylidodecyl oleate, iso-propyl myristate, triglyceril iso-stearate,coconut oil fatty acid triglyceride, olive oil, avocade oil, bees way,myristyl myristate, mink oil, ranoline, dimethylpolysiloxane, etc., oil,e.g., fat and oil, esters, higher alcohols, solders, silicone oil, etc.,ultra-violet ray absorbers, anti-oxidization agents, surface activeagents, moisture retainers, perfumes, water, alcohol and viscosityincreasing agents.

When the photochromic ultra-violet ray shield power according to theinvention is used for a cosmetics, the cosmetics may be powdery,cake-like, pencil-like, stick-like, paste-like, liquid-like,emulsion-like, cream-like, etc.

With the use of the photochromic flaky titanium oxide, molding surfacemay be removed with puff with difficulty of caking. In addition, theslip can be improved when the cosmetics is applied to the skin, thusimproving the property of use of the make-up preparation.

As shown, according to the invention by incorporating the photochromicultra-violet ray shield powder in compositions, typically cosmetics, itis possible to obtain photochromic property, which could not have beenattained with the prior art materials of cosmetics products. Besides,because of high ultra-violet ray shield effect, It is possible toeliminate adverse effects of excessive ultra-violet rays on the skin.Further, the composition is highly stable with respect to light, and itdoes not cause any fatigue phenomenons. Thus, it is possible to obtainstable products.

Further, photochromic titanium oxide is far more stable thanphotochromic organic materials.

The photochromic ultra-violet ray shield powder may be used for paintsas well as for cosmetics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the relation between the specific surface areaand calcinating temperature of titanium oxide;

FIG. 2 is a view illustrating a process of manufacture of photochroinictitanium oxide by a neutralization process;

FIG. 3 is a view illustrating a process of manufacture of photochromictitanium oxide by a urea process;

FIG. 4 is a graph showing the relation between the specific surface areaand calcinating temperature of titanium oxide samples having differentspecific surface areas: and

FIGS. 5 to 8 are graphs showing ultra-violet ray shield effects ofphotochromic ultra-violet ray shield powder according to the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Now preferred mode of carrying out the invention will be described withreference to the drawings, without any sense of limiting the invention.Proportions are shown in % by weight if they are not particularlyspecified.

Definition of the photochromic property

According to the invention, the photochromic property is tested asfollows.

4 g of photochromic ultra-violet ray shield powder is uniformlydispersed in 16 g of nitrocellulose lacker to form a dispersion. Thedispersion is coated on art paper using an applicator to form a coatingfilm with thickness of 76 μm. The coating film is then dried and used asa sample for photochromic property measurement under an opticalcondition that a lamp ("FL20.BLB " manufactured by Toshiba) and a lamp("FL20S.E" manufactured by Toshiba) are secured at a distance of 11 cmfrom each other. Distance adjustment of the sample is effected using anultra-violet ray intensity measuring apparatus ("SUV-T" manufactured byTolay Techno) such that the intensity of ultra-violet rays incident onthe same is 2 mW/cm².

Actual colorimetric measurements are done as follows

(1) The sample is colorimetrically measured after it has been left atroom temperature and in a dark place for about 10 hours, the measurementbeing made using a colorimeter ("CR-200" manufactured by Minolta).

(2) The sample is immediately colorimetrically measured when it isdarkened by irradiation with the ultra-violet rays for 30 minutes insame way described above.

(3) The irradiated sample is similarly colorimetrically measure afterleaving it at room temperature and in a dark place for 24 hours. Thephotochromic property is defined as

5≦A, and

B≦3,

where A represents the color difference ΔE between the color determinedin (1) and the color determined in (2), and B represents the colordifference ΔE between the color determined in (1) and the colordetermined in (3).

Relation between specific surface area and calcinating temperature

In order to study for the cause of reduction of the ultra-violet rayshield effect of titanium oxide powder having ultra-violet ray shieldeffect as a result of imparting the powder with the photochromicproperty the inventors examined the relation between the specificsurface area and calcinating temperature.

The titanium oxide having specific surface area of 98 m² /g wascalcinated at 600° to 1,000° C., and the specific surface area after thecalcinating was measured.

Results as shown in Table 1 and FIG. 1 were obtained.

                  TABLE 1                                                         ______________________________________                                        Calcinating temperature                                                                       Specific surface area (m.sup.2 /g)                            ______________________________________                                        Before calcinating                                                                            98                                                            600             66.3                                                          700             36.9                                                          800             15.5                                                          900             6.0                                                           1,000           3.5                                                           ______________________________________                                    

It will be understood frog Table 1 above that with the increase thecalcinating temperature the specific surface area is reduced, while theparticle size is increased,

In this way, with reduction of the specific surface area i.e., withincrease of the particle size, the ultra-violet ray shield effect offine particle titanium oxide powder is reduced.

Meanwhile, in the prior art for imparting titanium oxide with thephotochromic property, calcinating at about 600° C. or above is usuallyrequired, and photochromic ultra-violet ray shield powder lavingsatisfactory photochromic property and satisfactory ultra-violet rayshield effects has not been obtained.

The inventors, accordingly, conducted further investigations about thephotochromic property of fine particle titanium oxide.

Relation between the photochromic property and manufacture methodthereof

The photochromic property is influenced by the method of manufacture

Typical processes of imparting titanium oxide with the photochromicproperty are a neutralization process and an urea process.

Neutralization process

In the neutralization process, as shown in FIG. 2, titanium oxide isdispersed in deionized water, and he dispersion is stirred with ironchloride FeCl₃ added to it. The system is then neutralized by addingsodium hydroxide, and reacted at 80° to 90° C. for 2 hours. The reactedsystem is then filtered, and the residue is washed with water, thendried, then calcinated and then disintegrated.

Photochromic property is shown as color difference ΔE in case of usingrutile type titanium oxide as titanium oxide in Table 2, and in case ofusing anatase type titanium oxide in Table 3.

The restoration factor is given as:

(ΔE after ultra-violet ray irradiation-ΔE after leaving in darkplace)/(ΔE after ultra-violet ray irradiation)

The symbols shown under the numerical values of ΔE after ultra-violetray irradiation for 30 minutes and ΔE after leaving in dark place for 24hours concern judgment as to whether the values meets the definitionnoted above of the photochromic property (◯: meets Δ: substantiallymeets, X: fails to meet)

                  TABLE 2                                                         ______________________________________                                        Neutralization process                                                        (rutile type, specific surface area: 98 m.sup.2 /g, 0,7% Fe.sub.2             ______________________________________                                        O.sub.3)                                                                      Calcinating temperature                                                                      600     660    700   800  900                                  ΔE after ultra-violet                                                                  3.44    3.37   2.96  2.63 2.81                                 ray irradiation for 30 minutes                                                (A)            X       X      X     X    X                                    ΔE after leaving in                                                                    2.13    2.03   1.63  1.88 1.00                                 dark place for 60 minutes                                                     Restoration factor                                                                           38%     40%    45%   29%  65%                                  ΔE after leaving in                                                                    0.98    0.88   0.93  1.04 0.51                                 dark place for 24 hours                                                       (B)            ◯                                                                         ◯                                                                        ◯                                                                       ◯                                                                      ◯                        Restoration factor                                                                           78%     74%    69%   61%  82%                                  ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                        Neutralization process                                                        (anatase type, 98 m.sup.2 /g, 0.7% Fe.sub.2 O.sub.3)                          ______________________________________                                        Calcinating temperature                                                                      600     660    700   800  900                                  ΔE after ultra-violet                                                                  6.61    8.16   8.83  7.00 5.75                                 ray irradiation for 30 minutes                                                (A)            ◯                                                                         ◯                                                                        ◯                                                                       ◯                                                                      ◯                        ΔE after leaving in                                                                    3.65    5.76   6.66  5.95 2.34                                 dark place for 60 minutes                                                     Restoration factor                                                                           45%     30%    25%   15%  60%                                  ΔE after leaving in                                                                    3.07    5.02   6.09  5.52 2.17                                 dark place for 120 minutes                                                    Restoration factor                                                                           54%     39%    32%   22%  63%                                  ΔE after leaving in                                                                    1.88    3.15   3.96  4.02 1.45                                 dark place for 24 hours                                                       Restoration factor                                                                           72%     62%    56%   43%  75%                                  ______________________________________                                    

When the material titanium oxide used under the above conditions isrutile type, the color change degree is small, and substantiallysufficient photochromic property can not be obtained.

When the anatase type is used, the photochromic property can beextremely improved compared to the case of using the rutile type. Alsothe color chance degree is large, i.e. 660° to 700° C. However it issuitably about 600° C. when the restoration factor is also taken intoconsiderations.

Concerning the neutralization process, it is thought that thephotochromic property is influenced by the pH at the time of theneutralization.

Accordingly, the inventors conducted researches of the photochromicproperty with different pH settings in the neutralization process.Tables 4 to 6 show the results.

                  TABLE 4                                                         ______________________________________                                        Neutralization process                                                        pH: 8 (anatase type, specific surface area: 98 m.sup.2 /g, 0.7% Fe.sub.2      O.sub.3)                                                                      ______________________________________                                        Calcinating temperature                                                                       600     660      700   800                                    ΔE after ultra-violet                                                                   8.03    10.00    11.00 9.46                                   irradiation for 30 minutes                                                    (A)             ◯                                                                         ◯                                                                          ◯                                                                       ◯                          ΔE after leaving in                                                                     4.73    7.57     8.99  7.90                                   dark place for 60 minutes                                                     Restoration factor                                                                            42%     25%      19%   17%                                    ΔE after leaving in                                                                     2.68    5.01     6.34  5.57                                   dark place for 24 hours                                                       (B)             ◯                                                                         X        X     X                                      Restoration factor                                                                            67%     50%      43%   33%                                    ______________________________________                                    

                  TABLE 5                                                         ______________________________________                                        Neutralization process                                                        pH: 9 (anatase type, specific surface area: 98 m.sup.2 /g, 0.7% Fe.sub.2      O.sub.3)                                                                      ______________________________________                                        Calcinating temperature                                                                       600     660      700   800                                    ΔE after ultra-violet                                                                   6.31    7.61     9.59  4.59                                   ray irradiation for 30 minutes                                                (A)             ◯                                                                         ◯                                                                          ◯                                                                       Δ                                ΔE after leaving in                                                                     3.07    5.06     5.54  3.51                                   dark place for 60 minutes                                                     Restoration factor                                                                            52%     34%      48%   24%                                    ΔE after leaving in                                                                     1.71    3.08     3.66  2.42                                   dark place for 24 hours                                                       (B)             ◯                                                                         Δ  Δ                                                                             ◯                          Restoration factor                                                                            73%     60%      62%   48%                                    ______________________________________                                    

                  TABLE 6                                                         ______________________________________                                        Neutralization process                                                        pH: 10 (anatase type, 98 m.sup.2 /g, 0.7% Fe.sub.2 O.sub.3)                   ______________________________________                                        Calcinating temperature                                                                       600     660      700   800                                    ΔE after ultra-violet                                                                   6.17    7.05     8.09  5.28                                   irradiation for 30 minutes                                                    (A)             ◯                                                                         ◯                                                                          ◯                                                                       ◯                          ΔE after leaving in                                                                     2.70    4.24     5.73  4.26                                   dark place for 60 minutes                                                     Restoration factor                                                                            57%     40%      30%   20%                                    ΔE after leaving in                                                                     1.25    2.30     3.48  2.78                                   dark place for 24 hours                                                       (B)             ◯                                                                         ◯                                                                          Δ                                                                             ◯                          Restoration factor                                                                            80%     68%      57%   48%                                    ______________________________________                                    

As is clear from Tables 4 to 6, by using anatase type titanium oxide,satisfactory color charge degree can be obtained with any of the pH 8 to10. Considering the restoration factor, however, lower calcinatingtemperature is rather satisfactory. The color change degree is mostsatisfactory with pH 8. On the other hand, the restoration factor is thebetter the higher pH.

The relation between the photochroinic factor and pH was studiedsimilarly in the case of using titanium oxide with anatase/rutile=75/25as material.

Rutile type titanium oxide has a large refractive index and said to havegreater ultra-violet ray shield effect than anatase type titanium oxideprovided the particle size is the same. Therefore, when the ultra-violetray shield effect is considered, it is suitable to incorporate rutiletype titanium oxide.

Accordingly, researches were conducted on the Influence of incorporatingrutile type titanium oxide in anatase type titanium oxide or thephotochromic property.

Results are shown in Tables 7 to 9.

                  TABLE 7                                                         ______________________________________                                        Neutralization process                                                        pH: 8 (anatase/rutile = 75/25 48 m.sup.2 /g, 0.7% Fe.sub.2 O.sub.3)           ______________________________________                                        Calcinating temperature                                                                       600     660      700   800                                    ΔE after ultra-violet                                                                   5.13    5.07     3.86  1.76                                   ray irradiation for 30 minutes                                                (A)             ◯                                                                         ◯                                                                          X     X                                      ΔE after leaving in                                                                     3.03    3.14     2.52  1.32                                   dark place for 60 minutes                                                     Restoration factor                                                                            41%     39%      35%   25%                                    ΔE after leaving in                                                                     2.78    2.67     2.23  1.22                                   dark place for 20 minutes                                                     Restoration factor                                                                            46%     48%      42%   31%                                    ΔE after leaving in                                                                     1.08    0.73     0.36  0.52                                   dark place for 24 hours                                                       (B)             ◯                                                                         ◯                                                                          ◯                                                                       ◯                          Restoration factor                                                                            79%     86%      91%   70%                                    ______________________________________                                    

                  TABLE 8                                                         ______________________________________                                        Neutralization process                                                        pH: 9 (anatase/rutile = 75/25 48 m.sup.2 /g, 0.7% Fe.sub.2 O.sub.3)           ______________________________________                                        Calcinating temperature                                                                       600     660      700   800                                    ΔE after ultra-violet                                                                   4.92    4.30     4.57  1.26                                   ray irradiation for 30 minutes                                                (A)             Δ Δ  Δ                                                                             X                                      ΔE after leaving in                                                                     2.99    2.30     2.99  0.80                                   dark place for 60 minutes                                                     Restoration factor                                                                            40%     47%      35%   37%                                    ΔE after leaving in                                                                     2.55    1.95     2.60  0.68                                   dark place for 120 minutes                                                    Restoration factor                                                                            48%     55%      43%   46%                                    ΔE after leaving in                                                                     1.01    0.48     1.01  0.11                                   dark place for 24 hours                                                       (B)             ◯                                                                         ◯                                                                          ◯                                                                       ◯                          Restoration factor                                                                            80%     89%      78%   91%                                    ______________________________________                                    

                  TABLE 9                                                         ______________________________________                                        Neutralization process                                                        pH: 10 (anatase/rutile = 75/25 48 m.sup.2 /g, 0.7% Fe.sub.2 O.sub.3)          ______________________________________                                        Calcinating temperature                                                                       600     660      700   800                                    ΔE after ultra-violet                                                                   4.89    4.42     5.16  1.36                                   ray irradiation for 30 minutes                                                (A)             Δ Δ  ◯                                                                       X                                      ΔE after leaving in                                                                     2.59    2.42     3.32  0.76                                   dark place for 60 minutes                                                     Restoration factor                                                                            48%     45%      36%   44%                                    ΔE after leaving in                                                                     2.16    1.94     2.99  0.67                                   dark place for 120 minutes                                                    Restoration factor                                                                            56%     56%      42%   51%                                    ΔE after leaving in                                                                     0.94    0.70     1.16  0.16                                   dark place for 24 hours                                                       (B)             ◯                                                                         ◯                                                                          ◯                                                                       ◯                          Restoration factor                                                                            81%     84%      78%   88%                                    ______________________________________                                    

As is clear from Tables 7 to 9, the rutile type incorporated reduces thecolor change degree but provides for satisfactory restoration factor. Itis also to be understood that both the color change degree andrestoration degree are satisfactory in the neighborhood of pH 8.

In the overall consideration of the above, it will be understood thatwhen using the neutralization process it is suitable to use 75% or moreof anatase type titanium oxide and effect a treatment about pH 8.

Urea process

The urea process is usually said be based on mild conditions ofreaction, and it is possibly effective for prevention of the aggregationof titanium oxide.

In the urea process, as shown in. FIG. 3, titanium oxide is dispersed indeionized water and the system is stirred together with added ironchloride FeCI₃. Then, 5% sodium hydroxide aqueous solution was added forneutralization. Then, urea Is added, and to resultant system is reactedat 90° to 98° C. for 3 hours. Then, the reacted system is filtered, andthe residue is washed with water, then dried, then calcinated and thendisintegrated.

Tables 10 and 11 below show the photochromic property in terms of thecolor difference ΔE, respectively when rutile type titanium oxide isused as titanium oxide and when anatase type titanium oxide is used.

                  TABLE 10                                                        ______________________________________                                        Urea process                                                                  (rutile type, specific surface area: 98 m.sup.2 /g, 0.5% Fe.sub.2             ______________________________________                                        O.sub.3)                                                                      Calcinating temperature                                                                      600     660    700   800  900                                  ΔE after ultra-violet                                                                  2.84    2.92   2.66  2.19 2.91                                 ray irradiation for 30 minutes                                                (A)            X       X      X     X    X                                    ΔE after leaving in                                                                    1.39    1.77   1.35  1.35 0.77                                 dark place for 60 minutes                                                     Restoration factor                                                                           52%     40%    50%   39%  74%                                  ΔE after leaving in                                                                    0.98    0.80   0.57  0.60 0.45                                 dark place for 24 hours                                                       Restoration factor                                                                           66%     73%    79%   73%  85%                                  ______________________________________                                    

With rutile type titanium oxide used as material, the color changedegree is small, and sufficient photochromic property can not beprovided. The color change degree and restoration factor are thought tobe independent of the calcinating temperature.

                  TABLE 11                                                        ______________________________________                                        Urea process                                                                  (anatase type 98 m.sup.2 /g, 0.5% Fe.sub.2 O.sub.3)                           ______________________________________                                        Calcinating temperature                                                                      600     660    700   800  900                                  ΔE after ultra-violet                                                                  7.83    7.89   7.74  6.58 2.54                                 irradiation for 30 minutes                                                    (A)            ◯                                                                         ◯                                                                        ◯                                                                       ◯                                                                      X                                    ΔE after leaving in                                                                    3.26    4.19   5.18  5.54 1.16                                 dark place for 60 minutes                                                     Restoration factor                                                                           59%     47%    34%   16%  54%                                  ΔE after leaving in                                                                    2.49    3.61   5.01  5.23 1.04                                 dark place for 120 minutes                                                    Restoration factor                                                                           69%     55%    36%   21%  59%                                  ΔE after leaving in                                                                    1.69    2.14   3.24  3.95 0.69                                 dark place for 24 hours                                                       (B)            ◯                                                                         ◯                                                                        Δ                                                                             Δ                                                                            ◯                        Restoration factor                                                                           79%     73%    59%   40%  73%                                  ______________________________________                                    

With anatase type titanium oxide used as the material, the lower thecalcinating temperature the greater the color change degree as is seenfrom Table 11. In addition the restoration factor is the better thelower the calcinating temperature.

Further, in comparison to Table 3, the color change degree is great andalso the restoration factor is satisfactory in a low calcinatingtemperature range.

It will be understood from the above that calcinating at a temperaturelower than the common sense calcinating temperature in the prior art iseffective for imparting fine particle titanium oxide with thephotochromic property.

The fact that it Is possible to obtain satisfactory photochromicproperty at a low temperature, is very useful in view of the preventionof the aggregation during calcinating.

Accordingly the inventors conducted further researches concerning thephotochromic property in a low calcinating temperature range.

Low temperature range calcinating and photochromic property

The inventors conducted researches concerning the relation between thelow temperature calcinating and photochromic property.

                  TABLE 12                                                        ______________________________________                                        Neutralization process                                                        pH: 8 (anatase type, specific surface area: 98 m.sup.2 /g, Fe.sub.2           O.sub.3 0.7%)                                                                 ______________________________________                                        Calcinating temperature                                                                            560       580                                            ΔE after ultra-violet ray                                                                    7.16      7.38                                           irradiation for 30 minutes                                                    (A)                  ◯                                                                           ◯                                  {E after leaving dark place                                                                        3.47      4.18                                           for 60 minutes                                                                Restoration factor   52%       44%                                            ΔE after leaving in dark place                                                               2.80      3.59                                           for 120 minutes                                                               Restoration factor   61%       52%                                            ΔE after leaving in dark place                                                               1.58      2.21                                           for 24 hours                                                                  (B)                  ◯                                                                           ◯                                  Restoration factor   78%       71%                                            ______________________________________                                    

                  TABLE 13                                                        ______________________________________                                        Neutralization process                                                        pH: 9 (anatase type, specific surface area: 98 m.sup.2 /g, Fe.sub.2           O.sub.3 : 0.7%)                                                               ______________________________________                                        Calcinating temperature                                                                            560       580                                            ΔE after ultra-violet ray                                                                    6.13      5.80                                           irradiation for 30 minutes                                                    (A)                  ◯                                                                           ◯                                  ΔE after leaving in dark place                                                               2.26      2.46                                           for 60 minutes                                                                Restoration factor   64%       57%                                            ΔE after leaving in dark place                                                               1.75      2.05                                           for 120 minutes                                                               Restoration factor   72%       65%                                            ΔE after leaving in dark place                                                               0.93      1.18                                           for 24 hours                                                                  (B)                  ◯                                                                           ◯                                  Restoring factor     85%       80%                                            ______________________________________                                    

                  TABLE 14                                                        ______________________________________                                        Neutralization process                                                        pH: 10 (anatase type, specific surface area: 98 m.sup.2 /g, Fe.sub.2          O.sub.3 : 0.7%)                                                               ______________________________________                                        Calcinating temperature                                                                            560       580                                            ΔE after ultra-violet ray                                                                    6.26      7.02                                           irradiation for 30 minutes                                                    (A)                  ◯                                                                           ◯                                  ΔE after leaving in dark place                                                               2.10      3.26                                           for 60 minutes                                                                Restoration factor   67%       54%                                            ΔE after leaving in dark place                                                               1.35      2.75                                           for 120 minutes                                                               Restoration factor   79%       61%                                            ΔE after leaving in dark place                                                               0.60      1.76                                           for 24 hours                                                                  (B)                  ◯                                                                           ◯                                  Restoration factor   90%       75%                                            ______________________________________                                    

It will be understood from the above that by using the neutralizationprocess with anatase, type titanium oxide as material. sufficientphotochroinic property can be obtained at 560° to 580° C., which islower than the temperature of 600° C. thought to be necessary forimparting with the photochromic property in prior art.

Further researches were conducted in case of incorporating rutile typetitanium oxide.

                  TABLE 15                                                        ______________________________________                                        Neutralization process                                                        (anatase/rutile = 75/25, specific surface area: 48 m.sup.2 /g, Fe.sub.2       O.sub.3 : 1.0%)                                                               ______________________________________                                        Calcinating temperature                                                                       560     600     660   700                                     .increment.E after ultra-violet ray                                                           5.29    5.62    5.38  5.02                                    irradiation for 30 minutes                                                    (A)             ∘                                                                         ∘                                                                         ∘                                                                       ∘                           .increment.E after leaving in dark                                                            3.52    3.34    3.64  3.32                                    place for 60 minutes                                                          Restoration factor                                                                            33%     41%     32%   34%                                     .increment.E after leaving in dark                                                            2.56    2.91    3.06  2.89                                    place for 120 minutes                                                         Restoration factor                                                                            52%     48%     43%   42%                                     .increment.E after leaving in dark                                                            1.30    1.26    1.44  1.44                                    place for 24 hours                                                            (B)             ∘                                                                         ∘                                                                         ∘                                                                       ∘                           Restoration factor                                                                            75%     78%     73%   71%                                     ______________________________________                                    

                  TABLE 16                                                        ______________________________________                                        Neutralization process                                                        (anatase/rutile = 75/25, specific surface area: 48 m.sup.2 /g, Fe.sub.2       O.sub.3 : 2.0%)                                                               ______________________________________                                        Calcinating temperature                                                                       560     600     660   700                                     .increment.E after ultra-violet ray                                                           3.72    3.87    3.53  3.15                                    irradiation for 30 minutes                                                    (A)             X       X       X     X                                       .increment.E after leaving in dark                                                            2.41    2.45    2.43  1.93                                    place for 60 minutes                                                          120 minutes     1.85    2.11    2.16  1.70                                    24 hours        0.97    1.18    1.20  0.94                                    ______________________________________                                    

As is seen from Tables 15 and 16, where rutile type titanium oxide isincorporated by 25%, satisfactory photochromic property can be obtainedat 560° to 700° C. with Fe₂ O₃ provided by 1.0%. With Fe₂ O₃ provided by2.0%, however, the photochromic property is rather deteriorated.

Researches were conducted concerning low temperature calcinating, usingthe urea process. Tests were conducted by using anatase/rutile=50/50 asmaterial titanium oxide and varying the amount of Fe₂ O₃.

                  TABLE 17                                                        ______________________________________                                        Urea process                                                                  (anatase/rutile = 50/50, specific surface area; 98 m.sup.2 /g, Fe.sub.2       O.sub.3 : 0.7%)                                                               ______________________________________                                        Calcinating temperature                                                                       560     600     660   700                                     .increment.E after ultra-violet ray                                                           4.58    4.76    4.74  6.46                                    irradiation for 30 minutes                                                    (A)             Δ Δ Δ                                                                             ∘                           .increment.E after leaving in dark                                                            1.39    1.62    2.60  4.58                                    place for 60 minutes                                                          Restoration factor                                                                            70%     66%     46%   30%                                     .increment.E after leaving in dark                                                            1.26    1.37    2.14  4.11                                    place for 120 minutes                                                         Restoration factor                                                                            73%     72%     55%   37%                                     .increment.E after leaving in dark                                                            1.02    1.01    1.02  2.47                                    place for 24 hours                                                            (B)             ∘                                                                         ∘                                                                         ∘                                                                       ∘                           Restoration factor                                                                            78%     79%     79%   62%                                     ______________________________________                                    

                  TABLE 18                                                        ______________________________________                                        Urea process                                                                  (anatase/rutile = 50/50, specific surface area: 98 m.sup.2 /g, Fe.sub.2       O.sub.3 : 1.5%)                                                               ______________________________________                                        Calcinating temperature                                                                       560     600     660   700                                     .increment.E after ultra-violet ray                                                           536     5.75    6.10  806                                     irradiation for 30 minutes                                                    (A)             ∘                                                                         ∘                                                                         ∘                                                                       ∘                           .increment.E after leaving in dark                                                            1.87    2.65    3.62  6.05                                    place for 60 minutes                                                          Restoration factor                                                                            66%     54%     41%   25%                                     .increment.E after leaving in dark                                                            1.48    2.21    3.15  5.48                                    place for 120 minutes                                                         Restoration factor                                                                            73%     62%     49%   33%                                     .increment.E after leaving in dark                                                            0.94    1.17    1.78  3.56                                    place for 24 hours                                                            (B)             ∘                                                                         ∘                                                                         ∘                                                                       Δ                                 Restoration factor                                                                            83%     80%     71%   42%                                     ______________________________________                                    

                  TABLE 19                                                        ______________________________________                                        Urea process                                                                  (anatase/rutile = 50/50 specific surface area: 98 m.sup.2 /g, Fe.sub.2        O.sub.3 : 3.0%)                                                               ______________________________________                                        Calcinating temperature                                                                       560     600     660   700                                     .increment.E after ultra-violet ray                                                           4.44    4.45    5.62  6.61                                    irradiation for 30 minutes                                                    (A)             Δ Δ ∘                                                                       ∘                           .increment.E after leaving in dark                                                            1.87    1.78    3.52  5.15                                    place for 60 minutes                                                          Restoration factor                                                                            58%     60%     88%   23%                                     .increment.E after leaving in dark                                                            1.54    1.41    3.28  4.68                                    place for 120 minutes                                                         Restoration factor                                                                            66%     69%     42%   30%                                     .increment.E after leaving in dark                                                            0.89    0.66    2.09  3.50                                    place for 24 hours                                                            (B)             ∘                                                                         ∘                                                                         ∘                                                                       Δ                                 Restoration factor                                                                            80%     86%     63%   48%                                     ______________________________________                                    

As is seen from the above, where anatase/rutile=50/50 is used asmaterial titanium oxide for manufacture with the urea process, the colorchange degree is rather small if the calcinating is effected in a lowtemperature range. However, by slightly increasing the content of ironas active agent (i.e. Fe₂ O₃ : 1.5%) satisfactory photochromic propertycan be obtained at 560° to 700° C.

As shown above, it was made clear that so far as fine particle titaniumoxide is concerned sufficient photochromic property could be obtained ata calcinating temperature lower than the common sense calcinatingtemperature in the prior art.

The inventors further tried calcinating at 400° to 500° C.

                  TABLE 20                                                        ______________________________________                                        Urea process                                                                  (anatase type, specific surface area: 100 m.sup.2 /g, 0.7% Fe.sub.2           O.sub.3)                                                                      ______________________________________                                        Calcinating temperature                                                                             400       500                                           .increment.E after ultra-violet ray irradiation                                                     7.14      8.94                                          for 30 minutes                                                                (A)                   ∘                                                                           ∘                                 .increment.E after leaving in dark place for                                                        3.49      3.70                                          60 minutes                                                                    Restoration factor    52%       59%                                           .increment.E after leaving in dark place for                                                        3.01      2.74                                          120 minutes                                                                   Restoration factor    58%       70%                                           .increment.E after leaving in dark place for                                                        2.37      1.54                                          24 hours                                                                      (B)                   ∘                                                                           ∘                                 Restoration factor    67%       83%                                           ______________________________________                                    

                  TABLE 21                                                        ______________________________________                                        Urea process                                                                  (anatase type, specific surface area: 100 m.sup.2 /g, 1.5% Fe.sub.2           O.sub.3)                                                                      ______________________________________                                        Calcinating temperature                                                                             400       500                                           .increment.E after ultra-violet ray irradiation                                                     5.32      6.25                                          for 30 minutes                                                                (A)                   ∘                                                                           ∘                                 .increment.E after leaving in dark place for                                                        1.82      2.46                                          60 minutes                                                                    Restoration factor    66%       61%                                           .increment.E after leaving in dark place for                                                        1.53      2.06                                          120 minutes                                                                   Restoration factor    72%       68%                                           .increment.E after leaving in dark place for                                                        0.83      1.21                                          24 hours                                                                      (B)                   ∘                                                                           ∘                                 Restoration factor    85%       81%                                           ______________________________________                                    

                  TABLE 22                                                        ______________________________________                                        Urea process                                                                  (anatase type, specific surface area: 100 m.sup.2 /g, 3.0% Fe.sub.2           O.sub.3)                                                                      ______________________________________                                        Calcinating temperature                                                                             400       500                                           .increment.E after ultra-violet ray irradiation                                                     6.25      6.76                                          for 30 minutes                                                                (A)                   ∘                                                                           ∘                                 .increment.E after leaving in dark place for                                                        3.43      4.10                                          60 minutes                                                                    Restoration factor    45%       39%                                           .increment.E after leaving in dark place for                                                        2.98      3.71                                          120 minutes                                                                   Restoration factor    58%       45%                                           .increment.E after leaving in dark place for                                                        1.75      2.40                                          24 hours                                                                      (B)                   ∘                                                                           ∘                                 Restoration factor    72%       64%                                           ______________________________________                                    

As is seen from Tables 20 to 22, so far as fine particle titanium oxideis concerned, sufficient photochromic property can be imparted even at acalcinating temperature of about 400° C.

Amount of active agent added and photochromic pro

Researches were conducted concerning the amount of iron oxide added asactive agent and photochromic property.

When the amount of the active agent added is increased, coloring issometimes produced. In this case, the sample is no longer suited for theobservation of the photochromic property.

Accordingly, researches and investigations were conducted about thephotochromic property in case when the amount of the active agent addedis held low.

Test example 1 Synthesis from titanyl sulfate-iron (1)

800 ml of 2M TiOSO₄ aqueous solution was prepared, and FeCl₂ aqueoussolution such as to provide three different levels of % by weight of Fe₂O₃ with respect to TiO₂, i.e., 0.7, 1.5 and 3.0% were added to theTiOSO₄ aqueous solution. Subsequently, the resultant system was heatedfor 4 hours and then cooled down to room temperature, followed byfiltering and washing with writer. Then, the pH was adjusted to 8 with aNaOH aqueous solution, and the system was then washed with water againand dried.

This fine particle titanium oxide was calcinated at 500° to 800° C.

First, anatase type was investigated by varying the amount of Fe₂ O₃.

                  TABLE 23                                                        ______________________________________                                        Urea process                                                                  (anatase, specific surface area: 48 m.sup.2 /g, 0.7% Fe.sub.2 O.sub.3)        ______________________________________                                        Calcinating temperature                                                                       580     600     660   700                                     .increment.E after ultra-violet ray                                                           8.15    7.74    6.85  9.57                                    irradiation for 30 minutes                                                    (A)             ∘                                                                         ∘                                                                         ∘                                                                       ∘                           .increment.E after leaving in dark                                                            3.31    3.91    4.21  7.30                                    place for 60 minutes                                                          Restoration factor                                                                            59%     49%     39%   24%                                     .increment.E after leaving in dark                                                            2.44    3.31    3.79  6.80                                    place for 120 minutes                                                         Restoration factor                                                                            70%     57%     45%   29%                                     .increment.E after leaving in dark                                                            1.26    1.71    1.94  4.23                                    place for 24 hours                                                            (B)             ∘                                                                         ∘                                                                         ∘                                                                       X                                       Restoration factor                                                                            85%     78%     72%   56%                                     ______________________________________                                    

                  TABLE 24                                                        ______________________________________                                        Urea process                                                                  (anatase, specific surface area: 100 m.sup.2 /g, 1.5% Fe.sub.2 O.sub.3)       ______________________________________                                        Calcinating temperature                                                                       560     600     660   700                                     .increment.E after ultra-violet lay                                                           5.40    5.33    6.98  6.15                                    irradiation for 30 minutes                                                    (A)             ∘                                                                         ∘                                                                         ∘                                                                       ∘                           .increment.E after leaving in dark                                                            2.16    2.39    3.22  3.62                                    place for 60 minutes                                                          Restoration factor                                                                            60%     55%     54%   41%                                     .increment.E after leaving in dark                                                            1.86    2.33    2.74  2.94                                    place for 120 minutes                                                         Restoration factor                                                                            66%     56%     61%   52%                                     .increment.E after leaving in dark                                                            0.87    0.93    1.15  2.15                                    place for 24 hours                                                            (B)             ∘                                                                         ∘                                                                         ∘                                                                       ∘                           Restoration factor                                                                            84%     83%     84%   65%                                     ______________________________________                                    

                  TABLE 25                                                        ______________________________________                                        Urea process                                                                  (anatase, specific surface area: 100 m.sup.2 /g, 3.0% Fe.sub.2 O.sub.3)       ______________________________________                                        Calcinating temperature                                                                       560     600     660   700                                     .increment.E after ultra-violet ray                                                           4.82    5.29    5.34  5.83                                    irradiation for 30 minutes                                                    (A)             .increment.                                                                           ∘                                                                         ∘                                                                       ∘                           .increment.E after leaving in dark                                                            2.77    2.69    3.49  4.44                                    place for 60 minutes                                                          Restoration factor                                                                            43%     49%     35%   24%                                     .increment.E after leaving in dark                                                            2.50    2.42    3.23  4.30                                    place for 120 minutes                                                         Restoration factor                                                                            48%     54%     40%   26%                                     .increment.E after leaving in dark                                                            1.16    1.48    1.99  2.71                                    place for 24 hours                                                            (B)             ∘                                                                         ∘                                                                         ∘                                                                       ∘                           Restoration factor                                                                            76%     72%     63%   54%                                     ______________________________________                                    

It will be seen that when anatase type titanium oxide is used, excellentphotochromic property can be obtained with any amount of Fe₂ O₃.

Accordingly, researches were made on the status of the photochromicproperty exhibition using small quantity of active agent.

800 ml of 2M TiOSO₄ aqueous solution was prepared and FeCl₃ aqueoussolutions such as to provide five different levels of % by weight of Fe₂O₃ with respect to TiO₂, i.e., 0.01, 0.05, 0.125, 0.25 and 0.5% wereadded in the TiOSO₄ aqueous solution. Subsequently, the resultant systemwas heated or 4 hours and then cooled down to room temperature followedby filtering and washing with water. Then, the pH was adjusted to 8 witha NaOH aqueous solution, and the system was then washed again with waterand dried.

                  TABLE 26                                                        ______________________________________                                        600° C.                                                                ______________________________________                                        Fe.sub.2 O.sub.3                                                                              0.01   0.05    0.125                                                                              0.25  0.5                                 .increment.E ultraviolet                                                                      2.17   4.68    8.45 10.16 10.20                               irradiation for 30 minutes                                                    (A)             X      Δ ∘                                                                      ∘                                                                       ∘                       .increment.E after leaving                                                                    0.65   1.69    5.25 6.75  6.93                                in dark place for 60 minutes                                                  .increment.E after leaving                                                                    1.01   0.94    3.70 4.71  5.10                                in dark place for 180 minutes                                                 .increment.E after leaving                                                                    0.98   0.88    0.27 2.10  1.70                                in dark place for 24 hours                                                    (B)             ∘                                                                        ∘                                                                         ∘                                                                      ∘                                                                       ∘                       Restoration factor                                                                            55%    81%     77%  79%   83%                                 ______________________________________                                    

                  TABLE 27                                                        ______________________________________                                        700° C.                                                                ______________________________________                                        Fe.sub.2 O.sub.3                                                                              0.01   0.05    0.125                                                                              0.25  0.5                                 .increment.E after ultra-violet                                                               1.92   7.89    7.11 8.31  8.09                                ray irradiation for 30 minutes                                                (A)             X      ∘                                                                         ∘                                                                      ∘                                                                       ∘                       .increment.E after leaving                                                                    0.63   5.08    4.38 6.54  6.58                                in dark place for 60 minutes                                                  .increment.E after leaving                                                                    0.93   3.89    3.49 5.79  5.64                                in dark place for 180 minutes                                                 .increment.E after leaving                                                                    0.89   2.32    1.56 3.74  3.23                                in dark place for 24 hours                                                    (B)             ∘                                                                        ∘                                                                         ∘                                                                      ∘                                                                       ∘                       Restoration factor                                                                            54%    71%     78%  55%   60%                                 ______________________________________                                    

                  TABLE 28                                                        ______________________________________                                        800° C.                                                                ______________________________________                                        Fe.sub.2 O.sub.3                                                                              0.01   0.05    0.125                                                                              0.25  0.5                                 .increment.E after ultra-violet                                                               1.54   4.44    6.11 5.25  6.34                                ray irradiation for 30 minutes                                                (A)             X      Δ ∘                                                                      ∘                                                                       ∘                       .increment.E after leaving                                                                    1.05   2.66    3.71 3.54  4.43                                in dark place for 60 minutes                                                  .increment.E after leaving                                                                    1.18   2.19    2.89 3.04  3.78                                in dark place for 180 minutes                                                 .increment.E after leaving                                                                    1.00   1.24    1.49 1.42  1.52                                in dark place for 24 hours                                                    (B)             ∘                                                                        ∘                                                                         ∘                                                                      ∘                                                                       ∘                       Restoration factor                                                                            35%    72%     76%  73%   76%                                 ______________________________________                                    

As the result of the above test, it was made clear that when Usinganatase type titanium oxide, it is suitable to add an active agent by0.25 to 0.5% by weight in terms of Fe₂ O₃.

Low temperature calcinating tests were further conducted on theseparticularly satisfactorily photochromic samples.

                  TABLE 29                                                        ______________________________________                                        500° C.                                                                ______________________________________                                        Fe.sub.2 O.sub.3      0.25      0.5                                           .increment.E after ultra-violet ray irradiation                                                     13.39     17.88                                         for 30 minutes                                                                (A)                   ∘                                                                           ∘                                 .increment.E after leaving in dark place for                                                        7.64      13.69                                         60 minutes                                                                    .increment.E after leaving in dark place for                                                        3.02      11.44                                         180 minutes                                                                   .increment.E after leaving in dark place for                                                        0.44      6.11                                          24 hours                                                                      (B)                   ∘                                                                           X                                             Restoration factor    97%       66%                                           ______________________________________                                    

                  TABLE 30                                                        ______________________________________                                        550° C.                                                                ______________________________________                                        Fe.sub.2 O.sub.3      0.25      0.5                                           .increment.E after ultra-violet ray irradiation                                                     7.39      13.58                                         for 30 minutes                                                                (A)                   ∘                                                                           ∘                                 .increment.E after leaving in dark place for                                                        4.42      10.15                                         60 minutes                                                                    .increment.E after leaving in dark place for                                                        1.72      7.96                                          180 minutes                                                                   .increment.E after leaving in dark place for                                                        0.59      3.71                                          24 hours                                                                      (B)                   ∘                                                                           Δ                                       Restoration factor    92%       73%                                           ______________________________________                                    

It will be understood that very satisfactory color change degree andrestoration factor can be obtained by adding 0.25% of Fe₂ O₃ as activeagent and carrying out calcinating 500° to 550° C.

While the specific surface area of the material titanium oxide is 181 m₂/g, after calcinating at 600° C. the specific surface area is 45.9 m²/g. Thus, the specific surface area is maintained satisfactorily.

Photochromic titanium oxide and ultra-violet ray shield effect

From the above various experiments, it is made clear that for obtainingexcellent photochromic property by calcinating at a comparatively lowtemperature below 700° C. it is suitable to incorporate 50% or more ofanatase type titanium oxide and incorporate iron, if used as activeagent, by about 0.25% by weight in terms of Fe₂ O₃.

Meanwhile, the specific surface area and calcinating temperature o ftitanium oxide are very closely related to each other as noted earlier.

Accordingly, researches were conducted about the correlation between thecalcinating temperature and specific surface area.

FIG. 4 shows the relation between the specific surface area and thecalcinating temperature.

In the Figure, all the plots have downward slopes toward the right andsubstantially straight. They can be given as S=bT+a with S being thespecific surface area of powder after calcinating, T being thecalcinating temperature, and a and b constants

The plot line I the relation between the surface are S₁ and temperatureT in case amorphous titanium oxide of 700 m² /g, obtained by the liquidphase process from Ti(O-iso-Pr)₄, was calcinated at varioustemperatures.

As a result of this regressive analysis, the following relation could beobtained.

    S.sub.1 =-0.876T+768.

The phantom line plot II shows the relation between the specific surfacearea S₂ and temperature T in case when anatase type titanium oxide of100 m² /g, obtained by the liquid phase process from Ti(O-iso-Pr)₄, wascalcinated at various temperatures.

As a result of this regressive analysis, the following relation could beobtained.

    S.sub.1 =-0.125T+140

The dashed line plot III shows the relation between the surface area S₁and temperature T in case when amorphous titanium oxide of 100 m² /g,obtained by the gaseous phase process from TiCi₄, was calcinated atvarious temperatures.

As a result of this regressive analysis, the following relation could beobtained.

    S.sub.1 =-0.123T+129

Further, although not shown, in case when titanium oxide with a specificsurface area of 55 m² /g and with amorphous/rutile=75/25, obtained bythe gaseous phase process from TiCl₄, regressive analysis yielded thefollowing relation.

    S.sub.1 =-0.10T+90

Thus, it will be understood that The constant a assumes a value of thesum of the specific surface area S₀ before the calcinating and about 30to 70, while the constant b is reduced substantially in, inverseproportion to the specific surface area before the calcinating.

In either case, in either plot, when the calcinating temperature exceeds700° C., the specific surface area is undesirably extremely reduced.Further, regarding file particle titanium oxide, sufficient photochromicproperty can be obtained at a temperature not higher than 700° C.,particularly not higher than 600° C., as noted above. Thus, a suitablecalcinating temperature range is 400° C.≦T≦600° C.

When the material titanium oxide used has a specific surface area of 100m² /g or above, sufficient specific surface area and photochromicproperty can be obtained in a range of 700° C.

When the material titanium oxide used has a specific surface area of 100m² /g, it is possible to use b=-0.10 and a=S₀ +35 (S₀ being the specificsurface area of the powder after the calcinating) for satisfactorilycalculating the specific surface area of the powder after thecalcinating.

Thus, with titanium oxide having a specific surface area of 100 m² /g orbelow used as material, if the minimum specific surface area of thepowder after the calcinating is 25 m² /g, the upper limit of thecalcinating temperature can be calculated from

    25=-0.10T+(S.sub.0 +35)

    T=(S.sub.0 +10)/0.10

Accordingly, material titanium oxide containing 50% or more of anatasetype titanium oxide was actually calcinated at 700° C. or below, and theultra-violet ray shield effect of the calcinated material wasinvestigated.

First, the specific surface area of each photochromic titanium oxide wasinvestigated.

                  TABLE 31                                                        ______________________________________                                        Material                                                                            Specific                       Specific surface                         titanium                                                                            surface Treatment      calcinating                                                                           area after                               oxide area    process  Fe.sub.2 O.sub.3                                                                    temperature                                                                           calcinating                              ______________________________________                                        Anatase                                                                             98 m.sup.2 /g                                                                         Neutral- 0.7%  700° C.                                                                        39.2 m.sup.2 /g                                        ization                                                         Same  Same    Same     same  660     52.2                                     Same  Same    Same     same  600     67.0                                     Same  Same    Urea     same  700     40.0                                     Same  Same    Same     same  660     47.0                                     Same  Same    Same     same  600     68.5                                     ______________________________________                                    

It will be understood that each sample- of calcinated titanium oxide hasa specific surface area of 40 m² /g or above, that is, it maintainsparticle sizes 40 to 70 m² /g in terms of the specific surface arearange, which is particularly suitable with respect to the ultravioletscattering.

Specific researches were conducted concerning the ultra-violetscattering effects.

Samples were prepared as follows.

(1) Neutralization process (photochromic ultraviolet ray shield powdersamples 1 to 3)

100 g of titanium oxide (anatase type, specific surface area: 98 m² /g)was dispersed in 2,000 ml of deionized water. Then, 10.5 g of ironchloride FeCI₃ was added, and the system was stirred. Then, about 10 gof sodium hydroxide was added for neutralization to pH 8 (shield powdersample 1), pH 9 (shield powder sample 2) and pH 10 (shield powder sample3), followed by reaction at 80° to 90° C. for 2 hours. Then, each systemwas filtered, and the residue was washed with water and dried. The dryresidue was then calcinated at 600° C. and disintegrated. As comparativeexample, calcinating was effected at 800° C.

Each test sample was diluted to 5% in a blend solution composed of 95%of castor oil and 5% of "Cosmol^(T) " (Sorbitan sesqui oleate) and thencoated using an applicator to a thickness of 10 μm for measurement.

FIG. 5 shows the ultra-violet ray shield effect.

As is clear from the Figure, all the shield powder samples 1 to 3 showexcellent shield effect with respect to ultra-violet rays of 300 to 400nm. There was a trend for the slightly higher effect obtainable with thelower pH.

(2) Urea process (photochromic ultra-violet ray shield powder samples 4to 6)

40 g of titanium oxide (anatase type, 98 m² /g) was dispersed in 800 mlof deionized water, then 0.41 g of ion chloride FeCl1₃ was added, andthe system was then stirred. Then, 5 ml of 5% sodium hydroxides aqueoussolution was added for neutralization. Then, 1.29 g of area was addedand the system was reacted at 90° to 98° C. for 3 hours. Then, thesamples were filtered, and the residues were washed with water anddried. Then, calcinating was done at 400° C. (sample 4). 600° C. (sample5) and 700° C. (sample 6), and each sample was then disintegrated. Themeasurement was done in the same way as with the above samples 1 to 3.

FIG. 6 shows the ultra-violet ray shield effect.

As is clear from the Figure the more excellent ultra-violet ray shieldeffect is obtainable with the lower calcinating temperature.

(3) Urea process (photochromic ultra-violet ray shield powder samples 7and 8)

Titanium oxide (anatase type, 100 m₂ /g) was prepared such that Fe₂ was0.7%, and then calcinated at 560° C. (sample 7) and 600° C. (sample 8).

FIG. 7 shows the ultra-violet ray shield effect of the photochromicultra-violet ray shield powder samples.

It will be seen that in this case very excellent ultra-violet ray shieldeffect can be obtained compared to the cases of FIGS. 5 and 6.

Now, examples of the manufacture of the photochromic ultra-violet rayshield powder according to the invention will be described.

Example 1

While stirring a solution obtained by diluting 100 parts of titaniumtetra-iso-propoxide with 500 parts of iso-propanol, a solution obtainedby diluting 50 parts of water with 500 parts of iso-propanol, was addedfor hydrolysis.

To this suspension was added a solution obtained by dissolving 5 partsof ferrous chloride in ethanol, and the resultant system was subjectedto a surface treatment with its pH adjusted to about 10 using sodiumhydroxide. This suspension was condensed using suction filter means, andthen dried at 120 to obtain 40 parts of stable fine particle powder witha specific surface area of about 700 m² /g.

This fine particle powder was calcinated at the following temperatures.As a result, the following specific surface areas and photochromicproperties could be obtained.

                  TABLE 32                                                        ______________________________________                                        Calcinating temperature                                                                         400     500     600   700                                   ______________________________________                                        Specific surface area                                                                           475.7   278.6   197.3 165.2                                 .increment.E after ultra-violet                                                                 6.39    5.94    5.02  3.42                                  ray irradiation for 30 minutes                                                (A)               ∘                                                                         ∘                                                                         ∘                                                                       X                                     .increment.E after leaving in dark                                                              2.56    2.59    3.86  2.56                                  place for 60 minutes                                                          .increment.E after leaving in dark                                                              2.27    2.29    2.39  2.35                                  place for 120 minutes                                                         .increment.E after leaving in dark                                                              1.16    1.20    1.70  1.21                                  place for 24 hours                                                            (B)               ∘                                                                         ∘                                                                         ∘                                                                       ∘                         Restoration factor                                                                              81%     79%     66%   64%                                   ______________________________________                                    

Example 2

Anatase type titanium oxide with a specific surface area of 100 m² /gwas produced from TiOSO₄ by the liquid phase process, and photochromicultra-violet ray shield powder was produced by using 1.5% of Fe₂ O₃ asan active agent.

The following specific surface areas and photochromic properties couldbe obtained.

                  TABLE 33                                                        ______________________________________                                        Calcinating temperature                                                                       450    500     550  600   700                                 ______________________________________                                        Specific surface area                                                                         67.3   61.6    55.9 58.4  37.6                                .increment.E after ultra-violet                                                               6.39   5.62    5.49 5.99  7.77                                ray irradiation for 30 minutes                                                (A)             ∘                                                                        ∘                                                                         ∘                                                                      ∘                                                                       ∘                       .increment.E after leaving in                                                                 3.52   3.25    3.26 3.60  5.61                                dark place for 60 minutes                                                     .increment.E after leaving in                                                                 3.08   2.95    3.01 3.25  5.18                                dark place for 120 minutes                                                    .increment.E after leaving in                                                                 1.88   1.74    2.12 1.98  3.21                                dark place for 24 hours                                                       (B)             ∘                                                                        ∘                                                                         ∘                                                                      ∘                                                                       Δ                             Restoration factor                                                                            71%    70%     62%  67%   59%                                 ______________________________________                                    

FIG. 8 shows specific ultra-violet ray shield effects.

In the Figure, the relation between the ultra-violet ray shield degreeand the wavelength is shown in cases of calcinating temperatures of450°, 500°, 550°, 660° and 700° C. It will seen from the Figure thatwhile all the samples have excellent ultra-violet ray shield effects,the more satisfactory effects can be obtained the lower the calcinatingtemperature.

As for the difference, in the effect between the urea process and theneutralization processes, the effect was slightly better with theneutralization process, but the difference was not so much.

Example 3

In a first trough 100 parts of tetra-iso-propoxy titanium was heated atabout 200° C., in a second trough 500 parts of water was heated at about120° C., and air was introduced from each trough as carrier gas into anelectric furnace at 300° C. for hydrolysis. Further, in a third trough1.5 parts of zinc chloride was heated at about 800° C., and air wasintroduced from the trough into the same electric furnace for surfacetreatment. This powder was recovered using filter cloth to obtain 40parts of material anatase type titanium oxide with a specific surfacearea of 100 m² /g.

This powder was calcinated at 500° C. to obtain photochromicultra-violet ray shield powder with A=5.05, B=2.01 and specific surfacearea of 79.0 m² /g.

Examples of the composition using the photochromic ultra-violet rayshield powder as above according to the invention are given below. Eachcomposition showed excellent photochromic property and ultra-violet rayshield effect.

Composition example 1 Pressed powder

    ______________________________________                                        (1) Photochromic ultra-violet ray shield powder (sample                                                  5.2%                                               (2) Talc                   90.0%                                              (3) Iron oxide             2.5%                                               (4) Squalane               2.0%                                               (5) Preservative agent     0.2%                                               (6) Perfume                0.1%                                               ______________________________________                                    

(Method of manufacture)

The components (1) to (3) were mixed, and in this mixture the components(4) to (6) were thermally dissolved. The resultant system wasdisintegrated. The resultant particles were molded into the form ordishes, thus obtaining pressed powder.

Composition example 2 Powder foundation

    ______________________________________                                        (1)  Photochromic ultra-violet ray shield powder (sample                                                      20.0%                                         (2)  Talc                       10.0%                                         (3)  Sericite                   47.9%                                         (4)  Spherical nylon powder     8.0%                                          (5)  Red iron oxide             0.5%                                          (6)  Yellow iron oxide          1.0%                                          (7)  Black iron oxide           0.1%                                          (8)  Polydimethyl siloxane      5.0%                                          (9)  2-ethylhexyl palmitate     5.0%                                          (10) Sorbitan sesquioleate      1.5%                                          (11) Preservative agent         0.9%                                          (12) Perfume                    0.1%                                          ______________________________________                                    

(Method of manufacture)

The components (1) to (9) were mixed using a Henshell Mixer mixer. Tothis mixture was added what was obtained by thermally dissolving andmixing the components (9) to (12). The resultant system wasdisintegrated using a Pulverizer (by Hosokawa Mikuron). The resulantparticles were then molded into the form of a dish, thus obtaining apowder foundation.

Composition example 3 Dual purpose foundation

    ______________________________________                                        (1)  Photochromic ultra-violet ray shield powder (sample                                                      5.0%                                          (2)  Silicone-treated mica      46.25%                                        (3)  Silicone-treated talc      25.0%                                         (4)  Silicone-treated iron oxide                                                                              4.5%                                          (5)  Silicone-treated titanium oxide                                                                          6.5%                                          (6)  Trimethylolpropane triisostearate                                                                        5.0%                                          (7)  Squalane                   3.0%                                          (8)  Bees was                   2.0%                                          (9)  Sorbitan Trioleate         1.0%                                          (10) Preservative agent         0.5%                                          (11) Vitamin E                   0.05%                                        (12) Butylmethoxybenzoil methane                                                                              1.0%                                          (13) Perfume                    0.2%                                          ______________________________________                                    

(Method of manufacture)

The components (1) to (5) were mixed. To this mixture was added what wasobtained by thermally dissolving the components (6) to (13). The systemwas then disintegrated. The obtained particles were molded to the shapeof a disk to obtain a dual foundation.

Composition example 4 sun oil

    ______________________________________                                        (1) Liquid paraffin         69.75%                                            (2) Silicone oil           20.0%                                              (3) Vitamin E               0.05%                                             (4) Perfume                 0.2%                                              (5) Photochromic ultra-violet ray shield powder (sample                                                  10.0%                                              ______________________________________                                    

(Method of manufacture)

The components (1) to (4) were mixed, and then the component (5) wasadded and dispersed. Then, the system was degassed to obtain sun oil.The sun oil was darkened when exposed to sunlight, and also it hasexcellent ultra-violet ray shield effect.

Composition example 5 paint

    ______________________________________                                        (1) Photochromic ultra-violet ray shield powder (sample                                                   2.0%                                              (2) Acryloid B-66          22.0%                                              (3) Xylene                 56.0%                                              (4) Mineral spirit         20.0%                                              ______________________________________                                    

(Method of manufacture)

The components (1) to (5) were needed with a roll mill to obtain acrylicacid paint.

Composition example 6 Emulsified foundation

    ______________________________________                                        (1)  Photochromic ultra-violet ray shield powder (sample                                                      1.0%                                          (2)  Stearic acid               1.5%                                          (3)  Isostearic acid            0.3%                                          (4)  Isopropyl myristate        4.0%                                          (5)  Squalane                   12.0%                                         (6)  POE stearylether           1.5%                                          (7)  Glyceryl monooleate        0.5%                                          (8)  Cetylalcohol               0.5%                                          (9)  Talc                       10.0%                                         (10) Iron oxide                 0.5%                                          (11) Preservative agent          0.15%                                        (12) Triethanol amine           0.8%                                          (13) Propylene glycol           6.0%                                          (14) Montmorillonite            0.5%                                          (15) Refined water              60.55%                                        (16) Perfume                    0.2%                                          ______________________________________                                    

(Method of manufacture)

The components (12) to (15) were mixed and heated to 70° C. Then thecomponents (1) to (9) were mixed and disintegrated to be added to thefirst-mentioned mixture. Then, the oil components (2) to (8), (1) and(16) which were preliminary thermally dissolved and mixed at 70° C.,were, gradually added. Then the system was subjected to emulsifieddispersion. The resultant system was cooled down to room temperature toobtain an emusified foundation.

We claim:
 1. A photochromic ultra-violet ray shield powder comprisingparticles of titanium oxide having a specific surface area of at least25 m² /g and A≧5 and B≦3,wherein A represents a color difference ΔEbetween a color determined in test (1) and a color determined in a test(2), and B represents a color difference ΔE between a color determinedin test (1) and a color determined in a test (3), and in the test:(1) Asample is colorimetrically measured after it has been left a roomtemperature and in a dark place for about 10 hours, (2) A sample isimmediately colorimetrically measured when it is darkened by irradiationwith ultra-violet rays for 30 minutes in the same way as in test (1),and (3) An irradiated sample is similarly colorimetrically measuredafter leaving it at room temperature and in a dark place for 24 hours,and wherein said sample comprises an art paper having a drynitrocellulose lacquer coating about 76 μm thick and comprising 25 wt. %of said shield powder, and wherein photochromic property measurementsare made under an optical condition that a lamp of which λ_(max) is 350nm and power is 20 watts and a lamp of which λ_(max) is 313 nm and poweris 20 watts are secured a distance of 11 cm from each other, anddistance adjustment of the sample is effected using an ultra-violet rayintensity measuring apparatus such that intensity of ultra-violet raysincident on the sample is 2 mW/cm².